Three questions for Marla Malcolm Beck, who turned one small beauty boutique into a 28-store (and counting) multimillion-dollar business.

By Kate Sandoval

Who quits a big, successful corporate job to open a beauty store? Marla Malcolm Beck, that's who. After graduating from Harvard Business School and working as vice president of strategy at a private equity firm, she wanted to do something she felt passionate about; starting her own beauty business fit the bill. So in 1999, she opened her first Bluemercury boutique in Washington, D.C. We asked her about the best advice she ever got, her worst mistake, and what makeup she never leaves home without.

1. The best advice… Three months after I started Bluemercury, Sephora opened up two doors down. Everyone was telling me they were going to put us out of business. My husband, a serial entrepreneur, said, "Put your blinders on and keep doing your thing." That is exactly what I did. We kept our focus on creating a neighborhood store where you could get great products, spa services, and friendly, expert, honest advice. We made sure that we knew our customers intimately.

2. Her worst mistake… When we first launched, in 1999, there was a huge Internet craze, and before we knew it, we had blown through a million dollars to design a competitive website. But we built something so complicated that it was a nightmare to update, and it wasn't profitable for a long time. I learned not to listen to what everyone else tells you to do. Now I listen to my instincts and justify every dollar before we spend it.

3. Always in her bag… I keep a deep navy eyeliner (my two favorites are Trish McEvoy Powder Eye Liner in Arabian Nights with brush #11 and Bobbi Brown Long-Wear Gel Eyeliner in Indigo Ink) and three or four lip glosses (I tend to reach for lavenders and mauves like Laura Mercier Lip Glacé in Violet or Blush and T. LeClerc in Cyber Parme). I can quickly go from day to evening by changing my lip gloss. Oh, and I need my Nars Multiple in Maui—it's a highlighting stick that I swipe on my cheeks and lids.